Two circular rods, both of length l and having the same diameter, are placed end to end between rigid supports with no initial stress in the rods. the coefficient of linear expansion and young's modulus for rod a are αa and ya respectively; those for rod b are αb and yb respectively. both rods are "normal" materials with α> 0. the temperature of the rods is now raised by δt.

what is the stress f/a in the rods after heating? express the stress in terms of ? a, ? b, ya, yb, and ? t.

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?